Before the government approves a new industrial process in the UK it must have ensured that it won't harm either people or the environment. Mustn't it? That's what any sane person would expect. Any sane person would be wrong.

Here are the issues that must be resolved if we are to be assured that fracking is a safe and responsible process.

1. Contamination

There are two issues here: the chemicals injected into the rocks and the contaminants released by the fracturing. Both have the potential to pollute water supplies.

The Tyndall Centre at the University of Manchester reviewed the impacts of fracking in the only country where it has so far been commercially exploited, the United States. It found that fracking poses "significant potential risks to human health and the environment."

"The fracturing and 'flowback' fluids … contain a number of hazardous substances that, should they contaminate groundwater, are likely to result in potentially severe impacts on drinking water quality and/or surface waters/wetland habitats."

Amazingly, fracking fluids in the US are exempt from regulation. Companies are allowed to treat the composition of the fluids as trade secrets. There is little information on what they contain and what risks they might present.

But, using data on the chemicals being stored by these companies, the Tyndall Centre has been able to identify at least some of the substances being injected into the rocks there. Of 260 chemicals, it finds that 58 give rise to concern. Some are known carcinogens, some are suspected carcinogens, some are toxic to people, some are toxic to aquatic life, some are mutagenic (which means they can cause genetic defects) and some have reproductive effects.

The fluids returning to the surface carry not only the chemicals injected into the rocks, but also those picked up in travelling through them. Among these, the Tyndall report shows, are heavy metals and radioactive materials.

Both the fracking fluids and the flowback fluids can contaminate water either through the cracks forced open in the rocks by the fracking process, or through drilling bores through aquifers. In the US this has happened repeatedly. The Tyndall Centre found that water supplies have been contaminated not only by the fracking chemicals and dissolved pollutants from the rocks, but also by gas bubbling out through the cracks.

The documentary Gasland shows people turning their taps on and setting light to the water. In some cases, gas bubbling up from underground fractures has caused explosions in the basements of people's homes.

Cuadrilla's bore passes through an aquifer before it reaches the shale formation. The company's chief executive told the Guardian: "You never have control. Fractures will always go into the path of least resistance."

2. Water use

Fracking requires the use of very high volumes of water. The Tyndall Centre report warns that it "could put considerable pressure on water supplies at the local level in the UK." All the zones in the catchment in which Cuadrilla's operations at Preese Hall take place are classified by the Environment Agency as "over licensed", "over abstracted" or "no water available".

3. Greenhouse gases

The natural gas produced by fracking is the same simple chemical (methane) as the gas extracted by conventional means. When it is burnt, a given volume produces the same quantity of carbon dioxide as conventional gas does. Even so, the impact of shale gas on the atmosphere could be much greater than the impact of the same volume of conventional gas. Here's why.

More methane is likely to escape from the process of splitting rocks open than from drilling into conventional aquifers.

A paper published earlier this year in the journal Climatic Change found that methane emissions from shale gas fracking, "are at least 30% more than and perhaps more than twice as great as those from conventional gas." This, it says, boosts the climate changing impact of shale gas to such an extent that it is not just worse than conventional supplies, but worse even than coal, which is the most carbon-intensive fossil fuel. The paper found that, per unit of energy released, burning shale gas produces between 120% and 200% of the emissions produced by burning coal.

4. Raising fossil fuel reserves

Last month the Carbon Tracker Initiative worked out the proportion of current fossil fuel reserves that humanity can burn while keeping the chances of exceeding 2C of global warming to 20% or less. It found that current reserves contain roughly twice as much carbon as we can afford to release in the entire millennium.

Fossil fuel companies have already found far too much, in other words. It seems like madness to be prospecting for new reserves, especially new reserves with such a high potential to do harm, when we can't afford to use existing supplies.

So I asked the government some simple questions. The answers should stop anyone with a concern for human health or the environment in their tracks.

I asked to see the environmental impact assessment (EIA) for Cuadrilla's fracking operations, which it hopes to resume soon. Answer: there isn't one. The Department of Energy and Climate Change told me:

"The local planning authority has concluded that Cuadrilla's exploration activities do not fall within the criteria for EIA, and none has been performed."

I asked to see the Health Impact Assessment. This is what the government said:

"We are aware of no requirement on Cuadrilla to perform a health impact assessment, and we gather that they have not to date done so."

I asked to see the Life Cycle Analysis for the full impacts of extracting shale gas. The department told me:

"Government has not conducted a specific analysis of the size and variability of greenhouse gas emissions from the shale gas extraction process."

But, apparently disregarding the paper in Climatic Change, it produced the following guess:

"We would expect that shale gas should have a carbon footprint of the same order as natural gas from conventional onshore fields, and significantly lower than that of coal."

The government passed my questions about contamination to the Environment Agency (EA). I asked which chemicals have been licensed for underground injection by gas fracking operations in the UK.

It told me that the chemicals being used by Cuadrilla have been "assessed as 'non hazardous' under the Groundwater Directive".

But which chemicals are they? I had to press the agency for a list. It sent the following:

Hydrochoric acid; FR-40, which it calls "a blend of chemicals including Polyacrylamide"; Ucarcide, a bacteria-killing pesticide whose active substance is Glutaraldehyde; and Stimlube-W, which it simply described as "a polymer".

I asked the Environment Agency where it had got this list from. Cuadrilla sent it to them. Has the EA taken its own samples? Yes, or so it claims. But despite my repeated requests, it has failed to send me the results.

Has it analysed the trade-marked substances to determine whether they contain only the chemicals listed by Cuadrilla? I have now asked this question several times, and the agency, while giving minimal and uninformative answers to my other requests, has pointedly ignored it.

Worse still, in responding to me, the Environment Agency appears to have cut and pasted a phrase from Cuadrilla's website: "The fluids used by Cuadrilla are 99.75% composed of fresh water and sand." Is this how the agency sees its job? Lifting phrases from the site of a company it's supposed to be regulating? And has it ensured that this claim is true?

But there's nothing to worry about, the agency says, because "Groundwater is not present in the shale formation at the Preese Hall site."

As the disasters in the US demonstrate, the point is not just whether groundwater is present in the shale formation, but whether it is present in the overlying formations, through which the drill must pass, or into which the fractures might spread. At Preese Hall, Cuadrilla's drilling cuts through an aquifer to reach the shale.

Earlier this month, two campaigners hung banners from Blackpool tower in protest against Cuadrilla's plans to resume drilling at Preese Hall. In mid-September a group of activists will be setting up Camp Frack, not far from Cuadrilla's rig, to plan a campaign against the exploitation of shale gas. We should wish them luck.